Leasing apparatus and method

ABSTRACT

Apparatus for forming a lease on a plurality of superposed sheets of warp yarns including a reed frame carrying a plurality of hooked dents with adjacent dents separating the warp yarns into groups, and a control system connected with the reed frame to move the hooked dents in a serpentine path through each group of warp yarns to capture and separate alternate ones thereof to form a lease. A method of forming a lease on a plurality of superposed sheets of warp yarns including positioning each one of the warp yarns of each sheet between adjacent ones of a plurality of dents to form a group of warp yarns and simultaneously moving the hooked dents around every other one of the warp yarns in each group to form a lease.

0 United States Patent 051 3,678,548 Largeron et al. [4 1 July 25, 1972 [54] LEASING APPARATUS AND METHOD 2,706,846 4/1955 Cain et al ....28/40 [72] inventors: Louis Larger; Roger q both of 3,164,883 1/1965 Fleischer et al ..28/40 Arches France Primary Examiner-L0uis K. Rimrodt [73] Assignee: Societe Lorraine de Preparation Textile, Atwrney-shefman8shalloway Arches, France [22] Filed: Nov. 12, 1970 [57] ABSTRACT Apparatus for forming a lease on a plurality of superposed [21] APP]- NOJ 88,551 sheets of warp yarns including a reedl frame carrying a plurality of hooked dents with adjacent dents separating the warp 52 use: ..28/40,28/72.5 Yams and System cmnected 51 Int. Cl. ..'..D02h 9/00 reed frame the a serpemine Path [58] Field 6: Search ..28/40, 72.5 hmugh Warp Yams capture and Selma ternate ones thereof to form a lease, A method of forming a 56] References Cited lease on a plurality of superposed sheets of warp yarns including positioning each one of the warp yarns of each sheet UNlTED STATES PATENTS between adjacent ones of a plurality of dents to form a group v of Warp yarns and simultaneously moving the hooked dents 2,074,635 3 1937 Adams ..28/40 around every other one of the warp, yams in each group to 2,147,257 2/1939 Kaufmann ..28/40 formalease' 2,152,432 3/1939 Kaufmann ..28/40 2,344,721 3/1944 O'Connor ..28/40 10 Claims, 6 Drawing figures LEASING APPARATUS AND METHOD BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention pertains to leasing of warp yarns and, more particularly, to a method and apparatus for forming leases by moving a plurality of hooked dents in a serpentine path through a plurality of sheets of warp yarns such that con responding warp yarns in alternate sheets are captured to form a lease.

2. Discussion of the Prior Art One or more leases are generally formed at the end of a lap wound on a warp beam in order to facilitate the use of the warp beam in a later operation such as with a knitting machine or a weaving loom. During the leasing operation, alternate ones of the warp yarns are separated in shed-like fashion, and a rod or other suitable lease retention means is inserted between the leases or sheds to maintain the alternately separated warp yarns in position. That is, in a horizontal lap of warp yarns, the even numbered yarns are vertically separated from the odd numbered yarns to permit insertion of a horizontal rod to maintain the separation or lease. Thereafter, the ends of the warp yarns are easily selected for distribution, such as in the heddle mechanism of a loom.

The lap of warp yarns may be formed of yarns received directly from bobbins which unwind progressively during warping, or the warp yarns may be previously wound on section beams and thereafter wound from the section beams onto a warp beam, which operation is referred to as doubling.

The most common method of leasing prior to the present invention included placing the yarns from an even number of section beams in the successive intervals formed between the hookeddents of a multi-hook reed and alternately moving the sheets of warp yarns from the section beams and thereed so as to successively cross the even-numbered yarns and the oddnumbered yarns until the lease formed by the even-numbered yarns crossing the odd-numbered yarns is obtained at the level of the reed. According to this method, the reed is moved horizontally in a direction transverse to the direction of progression of the warp yarns while the sheets, which converge below the reed on a horizontal roller, are shifted vertically above the reed and held in position by movable lease bars. The handling of the lease bars is extremely delicate since the manuver requires the insertion between sheets, generally of great width, of a bar longer than the width and capable of withstanding the pressure of the lap. The bars must then be shifted vertically in order to insert the corresponding lap in the books of the reed, and the bars are removed once the lease is formed between the sheets. During the insertion and removal of the bar, catching or ravelling of the yarn often results, and the vertical movement required of the bars is extremely difficult. Another problem with this method, is that the bars are not easily inserted between appropriate sheets, and if the bars are improperly inserted a poor distribution of the even and odd numbered yarns results thereby requiring the operation to be performed again.

Prior art methods and apparatus for forming leases are exemplified by U.S. Pat. Nos. 2,074,635; 2,147,253; 2,147,257

and 2,706,846, which patents have the disadvantage of requiring either movement of both the sheets of warp yarns and the reeds or of being extremely complex and not admitting of fully automatic operation.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method and apparatus for automatically forming a lease on a plurality of warp yarns.

The present invention is generally characterized in apparatus for forming a lease during the warping of a plurality of warp yarns including a reed separating the warp threads into groups and having a hook associated witheach group, and means connected with the reed for automatically moving the hooks in a serpentine path through each of the groups to capture and separate alternate ones of the warp yarns in each of the groups to form a lease.

Another object of the present invention is to automatically move a plurality of hooks through a plurality of groups of warp yarns in a serpentine path to capture alternate ones of the warp yarns in each group to form a lease.

A further object of the present invention is to automatically control a reed frame such that hooked dents carried thereby are moved in a first direction, a second direction normal to the first direction and a third direction opposite to the second direction to capture alternate ones of warp yarns to form a lease.

The present invention has another object in that a method of forming a lease includes simultaneously moving a plurality of hooked dents around every other one of a plurality of grouped warp yarns to capture alternate ones of the warp yarns to form a lease.

Another object of the present invention is to provide a control system for a reed to alternately move the reed to perform a leasing operation.

Some of the advantages of the present invention over the prior art are that manual labor is not required during leasing operations, leases are formed quickly and accurately, and the leasing operation is fully automated.

Other objects and advantages of the present invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic side elevation of a warping machine utilizing the leasing apparatus of the present invention.

FIG. 2 is a front elevation of the leasing apparatus of the present invention.

FIG. 3 is a sectional view taken along line 33 of FIG. 2.

FIG. 4 is a schematic representation of a pneumatic control system for use with the leasing apparatus of the present inventron.

FIGS. 5 and 6 are enlarged schematic representations of the capturing and separating of alternate warp yarns by the leasing apparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A warping machine utilizing the leasing apparatus of the present invention is illustrated in FIG. 1 and includes section beams 10 and 12 rotatably mounted on a standard 14 and section beams 16 and 18 rotatably mounted on a standard 20. Section beams 10, 12, 16 and 18 are vertically spaced such that sheets of warp yarn delivered thereby are vertically spaced. That is, section beams 16 and 10 rotate counterclockwise to supply sheets 22 and 244 of warp yarns, respectively; and, section beams 12 and 18 rotate clockwise to supply sheets 26 and 28 of warp yarns, respectively. The sheets of warp yarns are maintained in vertically spaced relation by means of stationary lease bars 30.and pass through leasing apparatus 32 before converging at a take-up trio of rollers 34. From take-up trio 34 the warp yarns are drawn through a plurality of shed bars 36 and a spacing reed 38 to a return roller 40, and the warp yarns are supplied from roller 40 to a warp beam 42 for final warping.

The operation of the above-described warping machine,

with the exception of leasing apparatus 32, is well-known in the textile art and, accordingly, is not described in detail. It will be appreciated, of course, that the leasing apparatus of the present invention can be utilized with any warping machine or system and that the warping machine illustrated inFIG. l is for exemplary purposes only.

Leasing apparatus 32, as is best illustrated in FIGS. 2 and 3, includes a stationary inverted U-shape-d support 44 which has up-standing legs 46 and 48 secured to the base of the warping machine. A carriage 50 is adapted to move vertically in legs 46 and 48 of support 44 and includes vertically spaced, horizontally disposed, channel members 52 and 54 which are secured to vertical braces 56 and 58 at their ends adjacent legs 46 and 48, respectively. Member 52 of carriage 50 has wheels 60 and 62 rotatably mounted in opposite ends thereof and adapted to ride in channels 64 and 66 formed in legs 46 and 48, respectively; and, similarly, member 54 of carriage 50 has wheels 68 and 70 rotatably mounted at the ends thereof to ride in channels 64 and 66, respectively. To further stabilize vertical movement of carriage 50, four polyamide wheels 72 are mounted on brace 56 to contact the side walls of leg 46; and, similarly, four polyamide wheels 74 are mounted on brace 58 to contact the side walls of leg 48.

A reed frame 76 has a lower cylindrical support 78 which is slidably disposed in the channel formed in member 52 of carriage 50 and an upper support 80 which is generally U-shaped in cross-section and is slidably disposed in the channel formed in member 54 of carriage 50. A plurality of dents 82 are vertically disposed in reed frame 76 with their extremities secured in supports 78 and 80 such that the dents are equally horizontally spaced from one another. Each dent has a hook 84 extending therefrom and towards the right looking at FIG. 2.

A rod 86 is centrally secured to support 78 of reed frame 76 and is coupled by means of a piston 88 to a centering pneumatic cylinder 90 and by means of a piston 92 to a reciprocating pneumatic cylinder 94. Cylinders 90 and 94 are mounted on member 52 of carriage 50 such that reed frame 76 may be moved relative to caniage 50 by the cylinders, as will be explained hereinafter. A vertical pneumatic cylinder 96 is supported on a stationary base 98 and has a piston 100 connected with arms 102 and 104 which are secured to carriage 50 at upturned ends adjacent braces 56 and 58, respectively. Arm 102 carries a pneumatic switch 106 at a position adjacent leg 46, which switch 106 is adapted to engage and be actuated by bosses or actuators 108 and 110 mounted on leg 46 in vertically spaced positions. In a similar manner arm 104 carries a pneumatic switch 1 12 at a position adjacent leg 48, which switch 112 is adapted to engage and be actuated by bosses or actuators 114 and 116 mounted in vertically spaced positions on leg 48. Bosses 108, 110 and 116 are spaced from top to bottom such that as carriage 50 descends switch 106 is actuated by boss 108, switch 112 is actuated by boss 114, switch 106 is actuated by boss 1 l and switch 112 is actuated by boss 1 16 in succession.

A pneumatic control system for automatically controlling leasing apparatus 32 is illustrated in FIG. 4 and includes a source of compressed air 118 which is supplied to a pressure regulating valve 120. The outlet of valve 120 communicates with a switch 122 through a conduit 124 and with an electromagnetically controlled valve 126 through a conduit 128.

, The operation of switch 122 and valve 126 is controlled by an electrical circuit 130 which may include any conventional relay or electronic components to simultaneously energize actuators for switch 122 and valve 126. Switch 122 has an outlet communicating with an ascend inlet of vertical cylinder 96 through a conduit 132 and an outlet communicating with a descend inlet of vertical cylinder 96 through a conduit 134. Valve 126 has an outlet to supply air to centering cylinder 90 through a conduit 136 and an outlet to supply air to a distributor 138 through a conduit 140.

Distributor 138 has outlets supplying air to opposite ends of reciprocating cylinder 94 through conduit 142 and 144, respectively, and outlets supplying air to switches 106 and 112 through conduits 146 and 148, respectively. Switches 106 and 1 12 have outlets returning air to distributor 138 through conduits 150 and 152, respectively.

When electrical circuit 130 is energized switch 122 is actuated to supply air pressure to the descend inlet of vertical cylinder 76 through conduit 134 while valve 126 is actuated to supply air pressure to distributor 138 through conduit 140. When electrical circuit 30 is de-energized, switch 122 is operative to supply air pressure to the ascend inlet of vertical cylinder 96 and valve 126 is operative to stop'air flow through conduit 140 to distributor 138 and to supply air to centering cylinder 90 through conduit 136 to center reed frame 76. A governor communicates with the ascend inlet of vertical cylinder 96 to control the speed of descent of carriage 50. Air flow from distributor 138 is normally supplied through conduit 146, switch 106 and conduit 150 back to the distributor and through conduit 148, switch 112 and conduit 152 back to the distributor. However, when either switch 106 or 112 is actuated, air flows through conduit 142 or 144, respectively.

In operation, reed frame 76 is positioned such that hooks 84 are above the uppermost sheet 22 of warp yarns and is centered such that the warp yarns pass freely between adjacent dents 82. One warp yarn from each sheet is positioned between adjacent pairs of dents 82 to define a plurality of groups of four warp threads with each group associated with a hook 84. When it is desired to form a lease, control circuit 130 is energized to supply air to the descend inlet of vertical cylinder 96 through conduit 134 and switch 122 to cause carriage 50 to descend at a predetermined slow rate of speed and to commence the movement of the hooks in a tortuous or serpentine path through the groups of warp yarns.

The operation is best understood by reference to FIG. 5 wherein the movement of a single hook 84 and dent 82 past a group of warp yarns 22a, 24a, 26a, and 28a of sheets 22, 25, 26, and 28, respectively, is illustrated. When carriage 50 descends sufficiently such that switch 106 is actuated by boss 108, air flow through conduit 150 is stopped and air flow commences through conduit 142 to the left end of reciprocating cylinder 94. The air pressure in conduit 142 causes piston 92 to be moved to the right which through rod 86 moves reed frame 76 to the right from position A to position B. During the travel between positions A and B, all four warp yarns are moved to the right by the action of dent 82. After reaching position B the descension of carriage 50 causes hook 84 to capture warp yarn 22a; and, after travel from B to C, switch 112 is actuated by boss 114 to stop flow in conduit 152 and supply flow in conduit 144 to the right end of reciprocating cylinder 94 to move piston 92 to the left and therefore move reed frame 76 to the left to cause hook 84 to move from position C to position D.

At position D the descension of carriage 50 moves hook 84 between positions D and E without capturing warp yarn 24a, and when carriage 50 has moved to position E switch 106 will again be actuated by boss 110 to provide flow in conduit 142 and move piston 92 to the right. In a similar manner to the above-described motion between positions A and C, hook 84 moves between positions E and F, and after reaching position F descends to position G while capturing warp thread 26a in the same manner as warp thread 22a was captured. Thus, during travel between positions F and G hook 84 will capture both warp yarns 22a and 26a; and, once position G is reached,

' boss 116 actuates switch 112 to provide air flow in conduit 144 and move piston 92 to the left to move hook 84 between positions G and H in the same manner as above described with respect to positions C and D. Thereafter, carriage 60 continues to descend to position I which may arbitrarily be the end of the tortuous path.

The group of warp yarns will be as illustrated in FIG. 6 when position I is reached, and it will be seen from FIG. 6 that alternate warp yarns are gathered together to permit insertion of suitable lacing or lease retaining means. That is, a lease rod may be inserted between alternate ones of the warp yarns to maintain the lease.

As an example, the leasing apparatus of the present invention permits the leasing of a sheet of warp yarns having a length of 2,300 meters and a width of 1.20 meters wherein each sheet is derived from a section beam having 1,050 yarns, previously sized. In this manner 4,200 yarns of polyhexamethylene dipamide, 78 dtex, l7 filaments, twisted 25 turns per meter may be leased. 1,051 dents are required for such an operation in order that each warp yarn in each sheet extends between two adjacent dents. The lease bars 30 are stationary and operative such that in side elevation the sheets 22, 24, 26 and 28 are in superposed, substantially parallel relation as they are drawn through leasing apparatus 32 to take up trio 34 where the four sheets converge at three equi-angular intervals.

After a leasing operation is completed, switch 122 is deenergized by circuit 130 to supply air to the ascend inlet of vertical cylinder 96 through conduit 132 to move carriage 50 back up to its original pre-leasing position and simultaneously valve 126 is de-energized to stop the supply of air to distributor 138 through conduit 1140 and to supply air to centering cylinder 90 to center reed frame 76 in carriage 50.

While the present invention has been explained with respect to section beams in what is called a doubling operation, it is clear that the present invention can operate directly from a creel and in any suitable warping machine. Furthermore, it will be appreciated that the present invention is not limited to four section beams but rather any desired number of section beams may be utilized with the leasing apparatus of the present invention by merely providing the corresponding number of stationary leasing bars 30 and bosses along legs 46 and 48 of support 44. Similarly, the control of reed frame 76 to move in perpendicular directions laterally and vertically from the plane of movement of the warp yarns can be provided by any suitable control system such as electronic or mechanical controls utilizing appropriate circuitry, motors, rods and earns. The configuration of the tortuous or serpentine path through the superposed warp yarns may also be modified by making such path curved as in a sinusoidal wave or providing a serrated or zig-zag path. Any path which provides a movement of the hooks in a tortuous path between alternate ones of the warp yarns may be utilized.

The leasing apparatus of the present invention may be utilized to form leases on continuous or discontinuous fiber yarns independent of their nature and regardless of whether they are mineral, organic, natural, chemical and with or without a twist and is particularly suitable for the leasing of sheets of fine or delicate yarns such as continuous yarns formed of very fine polyamide filaments, polyethyleneteraphthalate filaments or acrylonitrile base filaments utilized in the manufacture of shear fabrics and other fine linen-like articles.

The method of forming a lease in accordance with the present invention essentially requires only the steps of positioning each of the warp yarns of each sheet between adjacent hooked dents to define a group of warp yarns between each pair of hooked dents, and simultaneously moving the hooked dents around every other one of the warp yarns in each group to capture and to separate alternate warp yarns to form the lease. The simultaneous movement of' the hooked dents around the warp yarns in each group permits the leasing of the warp yarns without requiring movement of the lease bars thereby greatly simplifying leasing methods known in the prior art.

The control mechanism for the leasing apparatus may be provided by mounting the control means consisting of the bosses and the switches in various positions, it being of prima ry concern only that the relative position of the carriage and the support 44 be sensed to control lateral movement of reed frame 76. That is, the vertical spacing of sheets 22, 24, 26 and 28 is determined at leasing apparatus 32 and the bosses are precisely spaced in accordance with the vertical spacing of the sheets to assure that the hooks 84 pass between alternate ones of the warp yarns in each group to provide the squared serpentine path for the hook through each group.

Inasmuch as the present invention is subject to many variations, modifications and changes in detail, all matter in the above description or shown in the accompanying drawings is intended to be illustrative only and not in any way limiting,

What is claimed is: a

1. Apparatus for forming a lease during the warping of a plurality of warp yarns comprising reed means separating said warp yarns into groups and having hook means for each of said groups each of said groups including more than two superposed warp yarns; and

moving means connected with said reed means for automatically moving said hook means in a serpentine path through each of said groups to capture and separate alternate ones of said warp yarns in each of said groups to form a lease, said serpentine path including a plurality of cycles, each cycle including movement past adjacent ones of said warp yarns to capture only one of said adjacent warp yams.

2. The invention as recited in claim 1 wherein said moving means includes a carriage movable in a first direction and said reed means includes a frame slidably disposed in said carriage and movable in a second direction normal to said first direction and a third direction opposite to said second direction.

3. The invention as recited in claim 2 wherein said apparatus includes support means for said carriage, and said moving means includes first control means mounted on said support means, second control means mounted on said carriage and positioning means responsive to contacting of said first and second control means to move said frame in said second and third directions.

4. The invention as recited in claim 3 wherein said positioning means includes a pneumatic cylinder mounted on said carriage and having a piston connected with said frame to move said frame in said second and third directions.

5. The invention as recited in claim 4 wherein said moving means includes a second pneumatic cylinder having a second piston connected with said carriage to move said carriage in said first direction and in a fourth direction opposite to said first direction.

6. The invention as recited in claim 5 wherein said positioning means includes a third pneumatic cylinder mounted on said carriage and having a third piston connection with said frame and said moving means includes a control switch operating said second and third cylinders to center said frame in said carriage and to move said carriage in said fourth direction to a pro-leasing position.

7. Apparatus for forming a lease on more than two superposed sheets of warp yarns, each of said sheets including a plurality of warp yarns, said apparatus comprising a reed frame disposed in a plane normal to said sheets of warp yarns;

a plurality of dents supported in spaced relation in said frame, each of said dents carrying a hook;

each of said warp yarns in each of said sheets being positioned between adjacent ones of said dents to define groups of more than two superposed warp yarns between each pair of said dents, each of said groups including one warp yarn from each of said sheets;

moving means connected with said reed frame for moving said reed frame in a first direction normal to said sheets of warp yarns, in a second direction normal to said first direction and said sheets of warp yarns, in a third direction opposite to said first direction and in said second direction to define a cycle; and

control means for automatically controlling said moving means to move said frame sequentially in said first, second, third and second directions for a plurality of consecutive cycles whereby said hooks capture and separate alternate ones of said warp yarns from the remainder of said warp yarns in each group to form a lease.

8. The invention as recited in claim 7 wherein said control means includes stationary control means, movable control means mounted on said moving means and switch means responsive to contacting of said stationary and movable control means to cause said moving means to move said reed frame in said first and third directions.

9. The invention as recited in claim 8 wherein said moving means includes a carriage movable in said second direction and said reed frame is slidably disposed in said carriage to be movable in said first and third directions.

110. A method of forming a lease on more than two super posed sheets of warp yarns comprising positioning each of said warp yarns of each of said sheets between adjacent ones of a plurality of dents each carrying a hook to define a group of more than two superposed warp yarns between each pair of adjacent dents, and

simultaneously moving said hooks past every other one of said warp yarns in each group with a serpentine movement to capture alternate ones of said warp yarns in each group in a single hook. 

1. Apparatus for forming a lease during the warping of a plurality of warp yarns comprising reed means separating said warp yarns into groups and having hook means for each of said groups each of said groups including more than two superposed warp yarns; and moving means connected with said reed means for automatically moving said hook means in a serpentine path through each of said groups to capture and separate alternate ones of said warp yarns in each of said groups to form a lease, said serpentine path including a plurality of cycles, each cycle including movement past adjacent ones of said warp yarns to capture only one of said adjacent warp yarns.
 2. The invention as recited in claim 1 wherein said moving means includes a carriage movable in a first direction and said reed means includes a frame slidably disposed in said carriage and movable in a second direction normal to said first direction and a third direction opposite to said second direction.
 3. The invention as recited in claim 2 wherein said apparatus includes support means for said carriage, and said moving means includes first control means mounted on said support means, second control means mounted on said carriage and positioning means responsive to contacting of said first and second control means to move said frame in said second and third directions.
 4. The invention as recited in claim 3 wherein said positioning means includes a pneumatic cylinder mounted on said carriage and having a piston connected with said frame to move said frame in said second and third directions.
 5. The invention as recited in claim 4 wherein said moving means includes a second pneumatic cylinder having a second piston connected with said carriage to move said carriage in said first direction and in a fourth direction opposite to said first direction.
 6. The invention as recited in claim 5 wherein said positioning means includes a third pneumatic cylinder mounted on said carriage and having a third piston connection with said frame and said moving means includes a control switch operating said second and third cylinders to center said frame in said carriage and to move said carriage in said fourth direction to a pre-leasing position.
 7. Apparatus for forming a lease on more than two superposed sheets of warp yarns, eacH of said sheets including a plurality of warp yarns, said apparatus comprising a reed frame disposed in a plane normal to said sheets of warp yarns; a plurality of dents supported in spaced relation in said frame, each of said dents carrying a hook; each of said warp yarns in each of said sheets being positioned between adjacent ones of said dents to define groups of more than two superposed warp yarns between each pair of said dents, each of said groups including one warp yarn from each of said sheets; moving means connected with said reed frame for moving said reed frame in a first direction normal to said sheets of warp yarns, in a second direction normal to said first direction and said sheets of warp yarns, in a third direction opposite to said first direction and in said second direction to define a cycle; and control means for automatically controlling said moving means to move said frame sequentially in said first, second, third and second directions for a plurality of consecutive cycles whereby said hooks capture and separate alternate ones of said warp yarns from the remainder of said warp yarns in each group to form a lease.
 8. The invention as recited in claim 7 wherein said control means includes stationary control means, movable control means mounted on said moving means and switch means responsive to contacting of said stationary and movable control means to cause said moving means to move said reed frame in said first and third directions.
 9. The invention as recited in claim 8 wherein said moving means includes a carriage movable in said second direction and said reed frame is slidably disposed in said carriage to be movable in said first and third directions.
 10. A method of forming a lease on more than two superposed sheets of warp yarns comprising positioning each of said warp yarns of each of said sheets between adjacent ones of a plurality of dents each carrying a hook to define a group of more than two superposed warp yarns between each pair of adjacent dents, and simultaneously moving said hooks past every other one of said warp yarns in each group with a serpentine movement to capture alternate ones of said warp yarns in each group in a single hook. 